The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight = 20 ± 7 kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550 μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20 μg kg(-1) for females and 10 μg kg(-1) for males) or a slow-release implant loaded with the same GnRHa (50 μg kg(-1) for females and 25 μg kg(-1) for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs kg(-1) and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs kg(-1). In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs kg(-1). The latency period was 48-72 h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70 ± 0.3% and 0.99 ± 0.02 mm, respectively, for GnRHa-implanted fish and were significantly higher (P < 0.05) compared to 30 ± 0.3% and 0.95 ± 0.03 mm, respectively, for injected fish. Few differences were observed in proximal composition and fatty acid profile and for all spawns mean (% dry weight) lipid content was 17.3 ± 3.0%, carbohydrate was 4.4 ± 1.9% and protein was 31.5 ± 6.4% and the essential fatty acids: Arachidonic acid (ARA, 20:4n-6) ranged between 0.9 and 1% (of total fatty acids), eicosapentaenoic acid (EPA 20:5n-3) 7.7-10.4% and docosahexaenoic acid (DHA 22:6n-3), 28.6-35.4%. All good quality spawns were obtained in the second and/or third spawn after GnRHa treatment, whereas all bad quality spawns were obtained either on the first spawn or after the fifth spawn. Both spawning protocols gave commercially viable (1,000,000+) numbers of good quality eggs that could form the basis of a hatchery production.

cies and also within some species. Mate selection and gamete release is a key factor that determines which genes or phenotypes are either passed to the next generation or lost (Berglund, 1997;Edward, 2015). Therefore, the description and understanding of a species spawning behaviour has implications for evolution and practical applications for aquaculture and conservation biology to maintain genetic pools and improve stocks. RESEARCH ARTICLE OPEN ACCESS AbstractSenegalese sole (Solea senegalensis) have a high potential for aquaculture that is hampered by reproductive behavioural problems. These problems result in limited breeder participation in spawning. The present study provided an ethogram and described mate selection and spawning of captive wild Senegalese sole. Two tanks of breeders were studied that had 29 and 25 breeders (mean weight = 1.6 ± 0.1 kg). The behaviour was studied during 20 periods of 24 hours: 10 periods where spawning events were recorded and 10 control periods without spawning events. Periods where spawning occurred had three times more locomotor activity than periods without spawning. Two distinct behaviours, termed the "following" behaviour and the "coupled swim", were only observed during periods with spawning. The courtship sequence (n=12) began with males predominantly involved in "following" behaviours, whilst females remained mainly stationary on the bottom of the tank. Males rested on the females and encouraged the females to begin swimming. When the female began to swim the male swam under the female and the pair made a "coupled swim" to the surface to release gametes. Gamete release was strictly in pairs of one male with one female. Failed "coupled swims" without gamete release were 5.6 times more frequent than successful "coupled swims". Mate selection was evident as the sole engaged in: paired spawning, males displayed to females, males encouraged females to spawn and females accepted or rejected the male's advances. The mate selection process provided the opportunity for fish to dominate the spawning and also demonstrated how fish were excluded from spawning.

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Previous studies on Senegalese sole (Solea senegalensis) indicated that cultured broodstock (first generation, G1) have lower tissue levels of arachidonic acid (20:4n-6, ARA) than wild counterparts. ARA is metabolized to form prostaglandins (PGs) that are involved in steroid production and follicle maturation in fish. In the present study the effects of different dietary levels of ARA on blood lipid and fatty acid composition, prostaglandin (PGF2α, PGF3α, PGE2 and PGE3) levels and plasmatic steroid levels (11-ketotestosterone, 11-KT, testosterone, T and estradiol, E2) in G1 Senegalese sole were studied. For this purpose, 12 groups of ten fish (1:1 male and female), were fed six diets (each diets was fed to two groups) with different dietary ARA levels over nine months (diets A=0.